1. Field of the Invention
This invention relates to a push-button for dispensing atomized liquids or creams under pressure through a nozzle provided in an elastically flexible body which is deformable, under the thrust of a pressurized liquid or cream originating from the stem of a pump, from a rest position in which the nozzle is closed by the end of a fixed shutter, to a dispensing position in which the nozzle has moved away from said end of the shutter.
2. Discussion of the Background
To dispense liquids in atomized form or pressurized creams, pumps are used having a stem on which there is mounted a push-button comprising a chamber into which the pressurized fluid arrives from the pump stem, this fluid being expelled to the outside via a discharge nozzle within which (if the fluid is a liquid) one or more profiled channels converge to impress a strong vorticose movement on the liquid before being expelled to the outside.
To achieve optimum atomization and prevent liquid dripping from the outside of the nozzle, this nozzle must be opened only when the pressure of the liquid reaching it exceeds a predetermined minimum value. The same requirement also exists if the fluid to be dispensed is a creamy substance.
The known art describes various types of push-buttons to be fitted onto the stems of pumps, in particular for delivering pressurized liquids, the purpose of such push-buttons being to achieve the aforesaid optimum atomization.
The U.S. Pat. No. 4,182,496 describes a push-button having a chamber communicating with the cavity within the stem and defined by a plug comprising within it the discharge nozzle which, when under rest conditions, is closed by the end of an appendix projecting from a piston sealedly movable--against the thrust of a spring--within said chamber. The pressurized liquid originating from the pump stem fills said chamber to cause the piston to move, so compressing the spring and freeing said nozzle, which however opens gradually with the result that liquid drips from the nozzle both when the nozzle is opened and closed.
European patent EP-A-0688608 describes a push-button (which obviates the drawbacks of the aforesaid US patent) in which the piston movable within the chamber in the push-button, is sealedly inserted into a cylindrical hole in a supplementary body housed in the chamber. The piston is released from this hole only after the end of the appendix--or shutter--projecting from the piston has withdrawn from the discharge nozzle, which is hence completely free when pressurized liquid is fed to it. The push-button of EP-A-0688608 has the drawback that the piston is traversed by a hole which connects together the two sides of the piston seal lip, so that it is practically impossible to prime the push-button at the moment of its initial use, whereas atomized liquid delivery ceases immediately on cessation of the pressurized liquid feed through the pump stem.
The U.S. Pat. No. 5,558,258 and the corresponding patent EP-A-0686433 describe a push-button similar to that of EP-A-0688608 but differing from it in that the piston seal lip is not holed, and in which the pressurized liquid originating from the pump stem is delimited by this seal lip, so that all the liquid present in the push-button chamber is expelled in atomized form under pressure, even when the arrival of pressurized liquid through said stem ceases.
Finally, patent application EP-A-0754499 describes a push-button similar to that of U.S. Pat. No. 5,558,258 but in which a lever system is provided for mechanically withdrawing the piston and for opening the discharge nozzle to allow expulsion of the air present in the push-button chamber at the moment of its initial use, ie at the moment in which the push-button is primed.
All the aforesaid known push-buttons have the drawback of being constructed by assembling at least five component parts, which considerably affects their production and assembly cost, it being easy to understand the difficulty involved in correctly and quickly assembling a relatively large number of component parts of very small dimensions.